The Fourth Amendment exclusionary rule began to unravel in United States v. Leon. The facts were compelling. Why exclude reliable physical evidence from trial when it was not the constable who blundered, but “a detached and neutral magistrate” who misjudged whether probable cause was present and issued a search warrant? Later cases applied the exception for “good faith” mistakes to a police officer who, pursuing a grudge against a suspect, arrested and searched him and his truck on the basis of a false and negligent report from a clerk in another county of an outstand­ing arrest warrant. The California Supreme Court recently applied this line of cases in People v. Robinson to support the conviction of a man whose DNA was taken by correctional officials who misunderstood the scope of the state’s DNA database statute. This Essay shows how the Robinson court exceeded the boundaries of the U.S. Supreme Court’s good-faith exception. It then proposes several ways to modify or confine the exception to achieve better protection of the Fourth Amendment right to be free from unreasonable searches and seizures.